The bill's chief sponsor, Democratic Rep. Bart Stupak of Michigan, said he had no doubt the FTC would be able to determine price gouging once the agency had a law to uphold.

The measure would establish the first federal law against energy price gouging. The FTC now can investigate price manipulation under antitrust laws. Currently, 29 states have price gouging statutes; enforcement varies widely.

Stupak's proposal only would go into effect — and then for just 30 days — if the president declared an energy emergency.

The bill calls for penalties of up to $150 million for companies and up to $2 million and 10 years imprisonment for individuals engaged in price gouging.

Twenty-nine state have various price-gouging statutes that vary widely.

The FTC has investigated allegations of price manipulation but failed to find widespread violations. In a report last year, the agency said an investigation after Hurricane Katrina hit in 2005 uncovered 15 incidents that could have been price gouging. But other factors also could have explained the high prices, it said.

The House passed the legislation by a vote of 284-141 as majority Democrats pushed for action ahead of the Memorial Day weekend, the traditional kickoff for the summer driving season.

Senate Democrats said they would take up energy legislation next month after finishing an immigration bill.